Bicruciate retaining tibial baseplate design and method of implantation

Abstract

A base component for a tibial implant has a lateral compartment and a medial compartment spaced from the lateral compartment defining an open central section therebetween. A connecting portion connects the medial and lateral compartments at an anterior end of the base component which anterior end is located adjacent the anterior tibia. The open central section of the base component intermediate the spaced medial and lateral compartments is open to a posterior end of the base component. The medial and lateral compartments have a bone contacting surface and a superiorly facing surface. The connecting portion has a curved anteriorly facing surface and has a first angled surface extending at an angle from adjacent the anterior end of the base component at a bone contacting surface of the connecting portion superiorly to a posterior end of the connecting portion. The first angled surface defining an anterior end of the open central section.

The invention claimed is: 
     
       1. A method for implanting a base component for a tibial implant comprising:
 providing a base component for a tibial implant comprising: a lateral compartment, a medial compartment spaced from the lateral compartment defining an open central section therebetween and a connecting portion connecting the medial and lateral compartments at an anterior end of the base component to be located adjacent the anterior tibia, wherein the central section of the base component intermediate the spaced medial and lateral compartments is open to a posterior end of the base component, wherein the medial and lateral compartments have a bone contacting surface and a superiorly facing surface, the connecting portion having a convexly curved anteriorly facing surface, the curved anteriorly facing surface curved convexly in an anterior direction along an arc lying in a sagittal plane bisecting the open central section of the tibial implant along a proximal to distal extent of the tibial component, and has a first inferiorly facing planar angled surface extending at a first angle from adjacent the anterior end of the base component at a bone contacting surface of the connecting portion proximally and posteriorly to a posterior end of the connecting element, the first planar angled surface defining an anterior end of the open central section at the sagittal plane bisecting the open central section of the tibial implant; 
 resecting a medial and lateral compartment of a proximal tibia to form two planar surfaces spaced from the anterior cruciate ligament and the posterior cruciate ligament; 
 forming a superiorly facing first angled surface on the proximal tibia intermediate the medial and lateral planar surfaces, the angled tibial surface extending from an anterior margin of the proximal tibia in a proximal-posterior direction to a proximal most surface of the tibia; and 
 mounting the base component on the proximal tibia with the base component medial and lateral compartment bone contacting surfaces respectively engaging the planar medial and lateral tibial compartments and the first angled superiorly facing surface on the proximal tibia contacting the first angled inferiorly facing surface on the base component from the anterior margin to the proximal most surface of the tibia. 
 
     
     
       2. The method as set forth in  claim 1  further comprising forming a second angled surface on the tibia intermediate the medial and lateral tibial compartments from the anterior margin of the proximal tibia in a proximal-lateral direction, the second angled tibial surface intersecting the first angled surface on the proximal tibia and engaging a second angled surface on the base component. 
     
     
       3. The method as set forth in  claim 2  wherein the first angled surface on the tibia is between about 20° to 70° and the second angled surface is between about 10° to 70°. 
     
     
       4. The method as set forth in  claim 1  wherein the first angled surface on the tibia forms an angle between about 20° to 70°. 
     
     
       5. A method for implanting a base component for a tibial implant comprising:
 resecting a proximal tibia by making a proximal to distal cut on a lateral side of a tibial central eminence; 
 resecting a proximal tibia by making a proximal to distal cut on a medial side of the tibial central eminence; 
 resecting an anterior surface of the tibial central eminence to form a first planar angled surface extending medially to laterally across the eminence and in an anterior to posterior direction and a distal to proximal direction, the planar angled surface extending along a single plane from an anterior most edge of the tibia to the proximal most surface of the tibial eminence; 
 resecting a medial and a lateral portion of the proximal tibia adjacent the medial and lateral cuts on the sides of the central eminence to form medial and lateral compartments having planar superior surfaces; and 
 implanting the base component of the tibial implant, the base component comprising a lateral and a medial compartment spaced apart by an open central section and having a first planar angled surface on an anterior bridge connecting the medial and lateral compartments by placing the medial and lateral compartments of the base component on the resected medial and lateral portions of the tibia and the tibial component first planar angled surface against the first planar angled surface of the tibial eminence, the first planar angled surface extending to the proximal most surface of the tibial eminence. 
 
     
     
       6. The method as set forth in  claim 5  wherein the first angled surface on the tibia forms an angle between about 20° to 70°. 
     
     
       7. The method as set forth in  claim 5  further comprising forming a second angled surface on the tibia intermediate the medial and lateral tibial compartments from an anterior margin of the proximal tibia in a proximal-lateral direction, the second angled tibial surface intersecting the first angled surface on the proximal tibia and engaging a second angled surface on the base component. 
     
     
       8. The method as set forth in  claim 7  further comprising providing the tibial component with a second angled surface extending from an anterior end of the first angled surface at a bone contacting surface laterally to a medially facing wall of the lateral compartment. 
     
     
       9. The method as set forth in  claim 8  wherein the first angled surface is between about 20° and 70° and the second angled surface is between about 10° and 70°. 
     
     
       10. The method as set forth in  claim 5  wherein an anterior surface of the anterior bridge of the tibial component is curved anteriorly along an arc lying in a sagittal plane bisecting the open central section of the tibial implant, the plane extending through the proximal tibia in a proximal-distal direction. 
     
     
       11. The method as set forth in  claim 10  wherein the curve of an anteriorly facing surface of the anterior bridge has a radius of curvature centered in a sagittal plane posteriorly of the anterior bridge. 
     
     
       12. The method as set forth in  claim 11  wherein the anterior bridge anteriorly facing surface is curved in a transverse plane. 
     
     
       13. The method as set forth in  claim 5  wherein the first angled surface portion on the tibia faces anteriorly and superiorly and the first angled surface on the base component faces posteriorly and interiorly.